1. Field
Example embodiments may relate to a semiconductor device, for example, to data storage devices using movement of a magnetic domain wall and methods of operating example embodiment devices.
2. Description of the Related Art
A general hard disk drive (HDD) is a device that may read and/or write information by rotating a magnetic recording medium in disk form and/or moving a reading/writing head above a magnetic recording medium. HDDs are non-volatile data storage devices that may be capable of storing 100 gigabytes (GB) of data or more and may be used as a storage device in computers.
A HDD may include moving mechanical systems. These mechanical systems may cause various mechanic faults if the HDD is moved or shocked, thereby decreasing mobility and/or reliability of the HDD. These mechanical systems may increase manufacturing complexity and/or costs of the HDD, increase power consumption, and/or generate noise. If HDDs are reduced in size, these problems associated with manufacturing complexity and cost may increase.
Data storage devices using magnetic domain manipulation may require fewer moving mechanical systems and may prevent or reduce problems associated with moving mechanical systems.
Magnetic regions that make up a magnetic body may be called magnetic domains. A single magnetic domain has identical direction of magnetic moment. Size and magnetization direction of magnetic domains may depend on the property, shape, size of a magnetic material and on external energy.
A magnetic domain wall may be a boundary between magnetic domains having different magnetization directions and may be moved by a current and/or a magnetic field applied to a magnetic material. A plurality of magnetic domains having one magnetization direction may be formed in a magnetic layer of a desired width and thickness, and magnetic domains and magnetic domain walls may be moved using a current and/or magnetic field.
Applying the principle of moving magnetic domain walls to information storage devices, magnetic domains may be passed through pinned reading/writing heads by movement of a magnetic domain wall, thereby enabling reading/writing without rotation of recording medium.
A related art data storage device using the moving principle of a magnetic domain wall according to the conventional art may include a U-shaped magnetic layer. The magnetic layer may be formed in a storage region having a plurality of magnetic domains and/or a buffer region, the length of which may be similar to that of the storage region. A reading head and/or a writing head may be formed under a middle portion of the magnetic layer. A current may be applied to the magnetic layer to pull and/or push the magnetic domain wall to perform reading and/or writing operations.
Related art storage devices may require a buffer region as large as that of a storage region, and the actual storage capacity of related art storage devices may be about half of the capacity of the physical storage region. Because it may be difficult to create a U-shaped magnetic layer using related art etching processes, it may be difficult to use related art storage devices. A writing head using an external magnetic field may not be successfully applied to a ferromagnetic layer having high magnetic anisotropic energy, and so magnetic layers of related art storage devices may be formed of a soft magnetic material. It may be difficult to stabilize movement of magnetic domain walls if the magnetic layer is formed of a soft magnetic material compared to a magnetic layer formed of a ferromagnetic material.